NIH - Linking language and cognition in infancy: Entry points and developmental change this proposal addresses fundamental issues of early language and conceptual development, and forges a precise link between them in infants' first year of life. Infants live in an enormously rich environment. Each day, they encounter new objects, while listening to a rich repertoire of sounds, including the sounds of their language. Amidst this richness, infants must identify the sounds of their native language and discover how these are linked to the world around them. Even before infants begin to speak, they identify the sounds of their language and link them to foundations of meaning. By 3 months of age, language supports infants' ability to form object categories. Initially, this link between language and cognition is quite broad: vocalizations of both human and non-human primates promote the formation of object categories. By 6 months, this link is tuned specifically to human vocalizations. The current proposal is designed to specify the scope of infants' initial link and t trace how it unfolds over the first year. Recruiting state-of-the-art analyses, this proposal will illuminate the developmental path infants take as they narrow in on the communicative signals of their species and link these signals to the foundations of meaning. Series I is designed to identify the range of signals that initially promote object categorization in human infants and how these are tuned over the first year. The studies examine infants' responses to vocalizations produced by human and non-human primates, mammals and birds, and also to manually-produced signals of sign language (ASL). Series II is designed to uncover how (and when) infants' exposure to language and other signals in the environment shapes the very possibility that they will link these signals to cognition. The studies, which examine infants' plasticity, wil pinpoint critical developmental windows for promoting language and conceptual development in all infants. Series III is designed to identify how infants come to interpret a signal (spoken or signed) as communicative. Taking infants' exquisite sensitivity to social cues (e.g., eye gaze) as a starting point, the studies consider whether infants interpret any signal (e.g., a tone sequence) as communicative if it is embedded within a rich communicative exchange. Humans are uniquely endowed with a natural capacity to build complex, flexible and creative systems of language and thought. This proposal, which forges a precise link between these systems, has far-reaching theoretical and practical implications. The proposed project broadens significantly the empirical and theoretical foundations of current research, and provides a window into the origins and evolution of infants' earliest links between conceptual and linguistic development. This work underscores the vital interaction between infants' natural endowments and the shaping role of the environment. It also builds a strong foundation for identifying infants with language delay or impairment, and serves as a springboard for designing targeted interventions to bolster their language and cognition.